CN116861610A - Method for determining porosity while drilling based on comprehensive logging parameters - Google Patents

Abstract

The invention discloses a method for determining the porosity while drilling based on comprehensive logging parameters, which includes: using a standardized mechanical specific energy model to obtain the standard mechanical specific energy value; using the standardized mechanical specific energy base value line formula to obtain the standard mechanical ratio Energy base value; use the ratio of the standard mechanical specific energy value to the standard mechanical specific energy base value as the formation physical property index, establish the relationship between the physical property index and porosity, and use the relationship to determine the porosity during drilling ; Solve the problem that conventional technical solutions can only qualitatively evaluate the physical properties of the reservoir, and cannot quantitatively calculate the porosity while drilling based on comprehensive logging parameters.

Description

Method for determining porosity while drilling based on comprehensive logging parameters

Technical field

The invention relates to the technical field of petroleum exploration, specifically a method for calculating porosity while drilling and a method for evaluating pore space types based on comprehensive logging parameters.

Background technique

At present, the main way to calculate reservoir porosity and identify and evaluate pore space types and structures is post-drilling evaluation. The measurement method mainly uses core measurement and logging in the laboratory; the relevant data of logging while drilling can be used. Porosity calculation and spatial type identification, but the measurement cost is high, and the porosity data is greatly affected by the wellbore conditions. Therefore, it is mostly used for geosteering in horizontal wells rather than for porosity calculation.

At the drilling/logging construction site, comprehensive logging engineering parameters collected while drilling have become commonly used data in exploration due to their low cost, easy construction, and high accuracy. However, due to the limitations of logging methods and the lack of modeling application of logging data , such as the invention patent titled Reservoir Physical Property Identification and Evaluation Method and Device While Drilling Based on Comprehensive Logging Parameters (CN201611126856.9), the intersection area S of the vertical and tangential bit work can be calculated while drilling, and the intersection area S can be calculated while drilling. Evaluate the size of the reservoir pores, and use the obtained drill bit work parameters to classify the physical properties of the reservoir. That is, the physical properties of the reservoir can only be evaluated qualitatively, and the porosity while drilling cannot be quantitatively determined based on the comprehensive logging parameters. Therefore, using logging parameters to calculate logging porosity while drilling and identify and evaluate pore space types is still a technical gap in the industry.

In recent years, due to the transformation of petroleum exploration from conventional to unconventional (tight oil and gas, shale oil and gas), there is an urgent need to obtain the porosity of the formation along with the drilling at the drilling and logging site, and to identify the pore space types to improve reservoir drilling. To ensure drilling safety, it is necessary to use well logging data to establish a method for determining porosity while drilling and identifying and evaluating pore space types.

Contents of the invention

In view of this, the present invention provides a method for determining porosity while drilling based on comprehensive logging parameters. Conventional technical solutions can only qualitatively evaluate the physical properties of the reservoir and cannot quantitatively conduct drilling while based on comprehensive logging parameters. Calculation of porosity.

In order to achieve the above-mentioned object of the invention, the method for determining the porosity while drilling based on comprehensive logging parameters is characterized by including:

Use the standardized mechanical specific energy model to obtain the standard mechanical specific energy value;

Use the standardized mechanical specific energy base value line formula to calculate the standard mechanical specific energy base value;

The ratio of the standard mechanical specific energy value to the standard mechanical specific energy base value is used as the physical property index of the formation, a relationship between the physical property index and porosity is established, and the porosity of the drill hole is determined using the relationship.

Preferably, the method for obtaining the standard mechanical specific energy value includes:

Collection and processing of comprehensive logging parameters;

The comprehensive logging parameters include drilling pressure, rotational speed, torque, mechanical drilling speed and drill bit diameter;

The processing is to correct and correct the weight on bit and the torque.

Preferably, the processed comprehensive logging parameters are substituted into the standardized mechanical specific energy model to calculate a standard mechanical specific energy value;

Data processing is performed on the standard mechanical specific energy values to eliminate outliers in the data.

Preferably, the standardized mechanical specific energy model is:

In the formula: E _B is the standard mechanical specific energy value, MPa; W _B is the regional representative standard weight on bit, kN; W _b is the corrected weight on bit, kN; n _B is the regional representative rotational speed, r/min; n is the rotation speed (from comprehensive logging 0.1m data), r/min; h is the relative height of drill bit wear, cm; ρ _B is the regional standard drilling fluid density, g/cm ³ ; ρ is the drilling fluid density, g/cm ³ ; E _m is the mechanical specific energy value, MPa; α is the weight on bit index, dimensionless, and the numerical value is related to the rock properties. It is obtained through core experiments to measure the relationship between mechanical specific energy and drilling weight; β is the rotational speed coefficient, dimensionless, and the numerical value is It is related to the rock properties and is experimentally obtained by measuring the relationship between mechanical specific energy and drilling weight through core experiments.

The mechanical specific energy value _{of Em} is calculated according to the following formula:

In the formula: E _m is the mechanical specific energy value, MPa; W _b is the corrected drilling weight, kN,; n is the rotational speed, r/min; M _is the corrected torque, N·m; V _ROP is the mechanical drilling speed, m/h; d _b is the diameter of the drill bit, mm.

Preferably, the data processing includes fitting processing and/or traversal while drilling and/or cluster analysis processing and/or smoothing processing and/or normalization processing.

Preferably, the formula of the standardized mechanical specific energy base value line is:

Sandstone: E _J =2.22ρ _d gH+25.37

Tuff in volcanic rocks: E _J =11.06ρ _d gH+250.30

Rhyolite in volcanic rocks: E _J =10.52ρ _d gH+334.02

Carbonate rock: E _J =4.33ρ _d gH+77.22

In the formula: E _J is the mechanical specific energy base value, MPa; ρ _d is the formation density, g/cm ³ ; g is the gravity acceleration, N/kg; H is the depth, m.

Preferably, the relationship between the physical property index and porosity is:

Sandstone: φ=-19.97ln(P)-0.2132

Volcanic rock: φ=-8.323ln(P)-0.1611

Carbonate rock: φ=-5.224ln(P)

In the formula: φ is the porosity of drilled holes, %; P is the physical property index.

The invention has the following beneficial effects:

Based on the physical meaning of the standard mechanical specific energy value and the standard mechanical specific energy base value, the method of the present invention creatively introduces the evaluation parameter of the formation physical property index to characterize the physical properties of the formation, and based on the fitting of the physical property index and the porosity measured in the laboratory The porosity of the formation while drilling can be obtained through the relationship, and then the reservoir can be quantitatively evaluated while drilling, thereby achieving the purpose of evaluating the physical properties of the reservoir while drilling, thus improving the timeliness of the physical property evaluation of the reservoir.

Description of the drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the present invention with reference to the accompanying drawings, in which:

Figure 1 is a flow chart of a method for determining porosity while drilling based on comprehensive logging parameters according to an embodiment of the present invention;

Figure 2A is a graph before data processing according to the embodiment of the present invention;

Figure 2B is a graph after data processing according to the embodiment of the present invention.

Detailed ways

The present invention will be described below based on examples, but it should be noted that the present invention is not limited to these examples. In the following detailed description of the invention, specific details are set forth. However, the present invention can be fully understood by those skilled in the art without detailed description.

Furthermore, those of ordinary skill in the art will appreciate that the drawings are provided solely to illustrate the objects, features and advantages of the present invention and are not actually drawn to scale.

At the same time, unless the context clearly requires it, the words "including", "includes" and other similar words in the entire specification and claims should be interpreted as an inclusive meaning rather than an exclusive or exhaustive meaning; that is, as a "including but not exclusive" meaning. limited to" meaning.

Figure 1 is a flow chart of a method for determining porosity while drilling based on comprehensive logging parameters according to an embodiment of the present invention. As shown in Figure 1, the method for determining porosity while drilling based on comprehensive logging parameters includes: Step S101 : Use the standardized mechanical specific energy model to obtain the standard mechanical specific energy value; Step S102: Use the standardized mechanical specific energy base value line formula to obtain the standard mechanical specific energy base value; Step S103: Use the standard mechanical specific energy value and the The ratio of the standard mechanical specific energy base value is used as the physical property index of the formation. A relationship between the physical property index and porosity is established, and the relationship is used to determine the porosity during drilling.

Specifically, the method for determining the porosity while drilling based on comprehensive logging parameters shown in Figure 1 will be described in detail with reference to the accompanying drawings to further describe the technical solution of the present disclosure.

Step S101: Use the standardized mechanical specific energy model to obtain the standard mechanical specific energy value. The obtaining process is:

1. Use comprehensive logging instrument to collect comprehensive logging parameters

Set the data collection step length of the comprehensive logging tool. Data will be collected and stored every 0.1m of drilling. The data includes: weight on bit, W, kN; rotational speed, n, r/min; torque, M, N·m; mechanical Penetration rate, vROP, m/h; drill bit diameter, db, mm.

2. Correction and error correction of weight on bit and torque data

The collected weight-on-bit and torque data come from the comprehensive logging instrument on the ground. In order to truly reflect the weight-on-bit and torque actually exerted by the drill bit when breaking rock underground, the weight-on-bit and torque from the comprehensive logging engineering data are corrected and carried out. Outlier removal processing.

Among them, the weight on bit and torque correction are calculated according to the following formula:

Weight on bit correction formula:

In the formula: W is the wellhead drilling pressure (from the 0.1m data of the comprehensive logging instrument), kN; W _b is the bottom hole drilling pressure, kN; μ _well is the friction coefficient of the well wall; α _k is the bottom well inclination angle.

Torque correction formula:

In the formula: M _total is the sum of drill bit torque and screw torque, N·m; W is wellhead drilling pressure, kN; D _b is drill bit diameter, m; μ _bit is the sliding friction coefficient related to drill bit type, which can be obtained through drill bit experiments Obtain; Q is the displacement per revolution of the drilling tool (from the 0.1m data of the comprehensive logging instrument), L/r; ΔP _p is the pressure drop at the inlet and outlet of the drilling tool, MPa.

The error correction processing of the weight on bit and torque data adopts the original data abnormal point inspection and error correction processing based on the 3δ method. The formula is as follows:

In the formula: δ is the random error; if the systematic error is not considered, then δ = x-μ; μ is the mathematical expectation of the measurement population X; σ is the standard deviation of the random error δ, which is also the standard deviation of the measurement population X.

After calculating the standard deviation based on the statistically obtained mean, and selecting the [μ-3δ, μ+3δ] interval as the error fluctuation range of the data, almost all the error data with uncertainty caused by the error can be included. included, thereby eliminating outliers such as weight on bit, rotational speed, and drilling time.

3. Use the standardized mechanical specific energy model to obtain the standard mechanical specific energy value

The standardized mechanical specific energy model described in the embodiment of the present disclosure is to obtain the mechanical specific energy sensitivity factors and response rules by designing different experiments with rock cores, and establish a standardized mechanical specific energy model formula.

The formula of the standardized mechanical specific energy model is as follows:

In the formula: E _B is the standard mechanical specific energy value, MPa; W _B is the regional representative standard weight on bit, kN; W _b is the corrected weight on bit, kN; n _B is the regional representative rotational speed, r/min; n is the rotation speed (from comprehensive logging 0.1m data), r/min; h is the relative height of drill bit wear, cm; ρ _B is the regional standard drilling fluid density, g/cm ³ ; ρ is the drilling fluid density, g/cm ³ ; E _m is the mechanical specific energy value, MPa; α is the weight on bit index, dimensionless, and the numerical value is related to the rock properties. It is obtained through core experiments to measure the relationship between mechanical specific energy and drilling weight; β is the rotational speed coefficient, dimensionless, and the numerical value is It is related to the rock properties and is experimentally obtained by measuring the relationship between mechanical specific energy and drilling weight through core experiments.

The mechanical specific energy value _{of Em} is calculated according to the following formula:

In the formula: E _m is the mechanical specific energy value, MPa; W _b is the corrected drilling weight, kN,; n is the rotational speed, r/min; M _is the corrected torque, N·m; v _ROP is the mechanical drilling speed, m/h; d _b is the diameter of the drill bit, mm.

4. Standard mechanical specific energy value processing

Mature computer data processing technology is used to filter, smooth and standardize the standard mechanical specific energy value. Before data processing, the curve shows more burrs and there may be abnormal points. When the reservoir thickness is thin, It will have a great impact on reservoir identification. After data processing, the curve becomes smooth and abnormal points are eliminated, so that the drawn standard mechanical specific energy curve can better reflect the spatial characteristics of the reservoir. The comparison of the curves before and after processing is such as Figure 2A and Figure 2B. Specific processing methods include:

1. The standard mechanical specific energy value is processed based on the Savitzky-Golay filter fitting method; the principle is based on polynomials in the time domain and fitted by the least squares method through a moving window.

2. Perform depth sequence mechanical specific energy traversal while drilling and clustering analysis on the standard mechanical specific energy values;

(1) From top to bottom, every 10m is a segment, find the maximum and minimum values of each segment, and record the depth corresponding to the maximum and minimum values (recorded in depth sequence); (E _B1 , E _B2 ,... , E _Bi , E _Bi+1 , E _Bi+2 , E _Bi+3 );

(2) According to the depth sequence, calculate the average value of each maximum value point;

(3) Define the threshold 30%

(4) Two consecutive values exceeding the threshold i+1, i+2 appear in the same direction (increase at the same time, or decrease at the same time); then point i is defined as the end point of the previous section, and the basic mechanical specific energy value of this section is The average mechanical specific energy of the segment.

(5) Starting from point i+1 as the starting value of the next segment, re-count, cluster, judge the threshold and determine the end point of the next segment.

3. Perform mechanical specific energy smoothing based on the five-point bell method on the standard mechanical specific energy value. The filtering formula is:

E _Bi =θ(E _Bi-2 +E _Bi+2 )+γ(E _Bi-1 +E _Bi+1 )+εE _Bi ;

Among them, the value of θ is 0.11, the value of γ is 0.24, and the value of ε is 0.3.

The standard mechanical specific energy value is smoothed based on the moving average method, and a series of averages are obtained by arithmetic averaging the data in the depth sequence using an item-by-item progression method.

4. Perform data normalization processing based on dispersion standardization on the standard mechanical specific energy value; use the dispersion standardization method to linearly transform the original data so that the result falls into the [0, 1] interval. The formula is as follows:

In the formula: is the normalized standard mechanical specific energy value, MPa; E _B is the standard mechanical specific energy value, MPa; E _Bmax is the maximum standard mechanical specific energy value in the section, MPa; E _Bmin is the minimum standard mechanical specific energy value in the section ,MPa.

Step S102: Calculate the standard mechanical specific energy base value using the standardized mechanical specific energy base value line formula

Through core experiments in the laboratory, the relationship between the mechanical specific energy value of sandstone, volcanic rock, and carbonate rock and the depth and density of the formation is determined, which is used as the standard mechanical specific energy base value line.

In this embodiment, the formula of the standardized mechanical specific energy base value line for different lithologies is as follows:

Sandstone: E _J =2.22ρ _d gH+25.37

Tuff in volcanic rocks: E _J =11.06ρ _d gH+250.30

Rhyolite in volcanic rocks: E _J =10.52ρ _d gH+334.02

Carbonate rock: E _J =4.33ρ _d gH+77.22

In the formula: E _J is the mechanical specific energy base value, MPa; ρ _d is the formation density, g/cm ³ ; g is the gravity acceleration, N/kg; H is the depth, m.

Step S103: Use the ratio of the standard mechanical specific energy value to the standard mechanical specific energy base value as the physical property index of the formation, establish a relationship between the physical property index and porosity, and use the relationship to determine the porosity during drilling.

This disclosure characterizes the physical properties of the formation by introducing the concept of formation physical property index P. The formation physical property index is the ratio of the standard mechanical specific energy value and the standard mechanical specific energy base value. The formation physical property index is located near 1, and 1 is a normally compacted ground layer; When the value is less than 1, the standard mechanical specific energy base value shows a negative anomaly, indicating that the physical properties of the formation are good. The lower the value, the better the physical properties of the formation.

The standard mechanical specific energy value and standard mechanical specific energy base value are calculated through comprehensive logging parameters such as drilling pressure and torque collected by the comprehensive logging tool while drilling.

According to the following formula, the formation physical property index is obtained.

In the formula: P is the physical property index, dimensionless; E _J is the standard mechanical specific energy value, MPa; E _B is the standard mechanical specific energy value, MPa.

Using core samples of different lithologies, the relationship model between physical property index and experimentally measured porosity was fitted through laboratory core experiments.

In this embodiment, the relationship between physical property index and porosity is as follows:

Sandstone: φ=-19.97ln(P)-0.2132

Volcanic rock: φ=-8.323ln(P)-0.1611

Carbonate rock: φ=-5.224ln(P)

In the formula: φ is the porosity of drilled holes, %; P is the physical property index.

It can be seen from the above description that the formation physical property index can be calculated in real time through the comprehensive logging parameters collected by the comprehensive logging instrument, and then the porosity along the drilling can be obtained.

Based on the technical solution of this embodiment, on the one hand, in the traditional mechanical specific energy model formula, the mechanical specific energy value is affected by geological factors such as formation lithology, rock strength, abnormal pressure, as well as drill bit structure, drilling parameters, drilling process conditions, The influence of engineering factors such as bottom hole conditions. The disclosed method standardizes the traditional mechanical specific energy model, processing the actual drilling pressure, rotational speed, hydraulic factor parameter values and corresponding actual drilling speed values during drilling into unified standardized parameter values, eliminating the influence of engineering factors and The influence of cross-well parameters makes the standard mechanical specific energy value contain formation skeleton strength and formation physical property information, which can reflect changes in geological physical properties.

On the other hand, the mechanical specific energy base value line in the traditional method does not have strict geological significance. Generally, the average value of the mechanical specific energy in a certain well section is used. The determination of the average value is based on the user's subjective understanding, taking a section or The mechanical specific energy value within several well depth intervals is calculated, so it is greatly affected by human factors in actual applications, resulting in large differences in the physical property evaluation results. The disclosed method uses laboratory core samples to obtain core skeleton strength data through micro-drilling experiments and triaxial stress experiments. Through data processing, a mechanical specific energy basic value line equation that represents the strength of the core skeleton is established to establish a basis that can reflect the strength of the formation rock or the porosity of the rock. The overall change of the mechanical specific energy base value line. The geological significance of this standard mechanical specific energy base value line is that the top-down mechanical specific energy value does not take into account the effects of secondary pores and fractures (dissolution, tectonic stress, biological effects, etc.) - The change curve of burial depth and the standardized mechanical specific energy base value line can reflect the overall changes in rock strength or rock porosity in a certain block.

Then, the standard mechanical specific energy value and the standard mechanical specific energy base value are calculated through the engineering parameters such as bit pressure and torque collected by the comprehensive logging tool while drilling.

Finally, based on the physical meaning of the standard mechanical specific energy value and the standard mechanical specific energy base value, the disclosed method creatively introduces the evaluation parameter of the formation physical property index to characterize the physical properties of the formation, and based on the difference between the physical property index and the porosity measured in the laboratory The fitting relationship can be used to obtain the porosity of the formation while drilling, which can then quantitatively evaluate the reservoir while drilling, achieving the purpose of evaluating the physical properties of the reservoir while drilling, thereby improving the timeliness of the physical property evaluation of the reservoir.

The above-described embodiments are only to express the implementation of the present invention. The descriptions are relatively specific and detailed, but they should not be construed as limiting the patent scope of the present invention. It should be noted that those of ordinary skill in the art can also make several modifications, equivalent substitutions, improvements, etc. without departing from the concept of the present invention, which all fall within the protection scope of the present invention. Therefore, the scope of protection of the patent of the present invention should be determined by the appended claims.

Claims (7)

1. A method for determining the porosity while drilling based on comprehensive logging parameters, which is characterized by including: Use the standardized mechanical specific energy model to obtain the standard mechanical specific energy value; Use the standardized mechanical specific energy base value line formula to calculate the standard mechanical specific energy base value; The ratio of the standard mechanical specific energy value to the standard mechanical specific energy base value is used as the physical property index of the formation, a relationship between the physical property index and porosity is established, and the porosity of the drill hole is determined using the relationship. 2. The method for determining the porosity while drilling based on comprehensive logging parameters according to claim 1, characterized in that the method for obtaining the standard mechanical specific energy value includes: Collection and processing of comprehensive logging parameters; The comprehensive logging parameters include drilling pressure, rotational speed, torque, mechanical drilling speed and drill bit diameter; The processing is to correct and correct the weight on bit and the torque. 3. The method for determining porosity while drilling based on comprehensive logging parameters according to claim 2, characterized by: Substitute the processed comprehensive logging parameters into the standardized mechanical specific energy model to calculate a standard mechanical specific energy value; Data processing is performed on the standard mechanical specific energy values to eliminate outliers in the data. 4. The method for determining porosity while drilling based on comprehensive logging parameters according to claim 3, characterized in that the standardized mechanical specific energy model is: In the formula: E _B is the standard mechanical specific energy value, MPa; W _B is the regional representative standard weight on bit, kN; W _b is the corrected weight on bit, kN; n _B is the regional representative rotational speed, r/min; n is the rotation speed (from comprehensive logging 0.1m data), r/min; h is the relative height of drill bit wear, cm; ρ _B is the regional standard drilling fluid density, g/cm ³ ; ρ is the drilling fluid density, g/cm ³ ; E _m is the mechanical specific energy value, MPa; α is the weight on bit index, dimensionless, and the numerical value is related to the rock properties. It is obtained through core experiments to measure the relationship between mechanical specific energy and drilling weight; β is the rotational speed coefficient, dimensionless, and the numerical value is It is related to rock properties and is experimentally obtained through core experiments to measure the relationship between mechanical specific energy and drilling weight; The mechanical specific energy value _{of Em} is calculated according to the following formula: In the formula: E _m is the mechanical specific energy value, MPa; W _b is the corrected drilling weight, kN,; n is the rotational speed, r/min; M _is the corrected torque, N·m; V _ROP is the mechanical drilling speed, m/h; d _b is the diameter of the drill bit, mm. 5. The method for determining porosity while drilling based on comprehensive logging parameters according to claim 4, characterized by: The data processing includes fitting processing and/or traversal while drilling and/or cluster analysis processing and/or smoothing processing and/or normalization processing. 6. The method for determining the porosity while drilling based on comprehensive logging parameters according to any one of claims 1 to 5, characterized in that the standardized mechanical specific energy base value line formula is: Sandstone: E _J =2.22ρ _d gH+25.37 Tuff in volcanic rocks: E _J =11.06ρ _d gH+250.30 Rhyolite in volcanic rocks: E _J =10.52ρ _d gH+334.02 Carbonate rock: E _J =4.33ρ _d gH+77.22 In the formula: E _J is the mechanical specific energy base value, MPa; ρ _d is the formation density, g/cm ³ ; g is the gravity acceleration, N/kg; H is the depth, m. 7. The method for determining porosity while drilling based on comprehensive logging parameters according to claim 6, characterized in that the relationship between the physical property index and porosity is: Sandstone: φ=-19.97ln(P)-0.2132 Volcanic rock: φ=-8.323ln(P)-0.1611 Carbonate rock: φ=-5.224ln(P) In the formula: φ is the porosity of drilled holes, %; P is the physical property index.